Which of the following is the first strategy in. the management of chronic obstructive lung disease?

There is a strong dose-response relationship between the intensity of smoking,expressed as pack years, & the developmant of COPD,expressed as decline in FEV1.It has been shown that middle-aged smokers who were able to successfully stop smoking experienced a significant improvement in the rate of decline in pulmonary function.Successful smoking cessation can be enhanced by pharmacological approaches like bupropion;nicotine replacement therapy and varenicline,a nicotinic acid receptor agonist/antagonist. Reference:Harrison's medicine-18th edition,page no:2157.